Hi i am wanting to buy a 91 305tpi wiring harness and ecm and was wondering if i could put that to my 91 RS that i wanna convert to a 350 tpi. If i can what else would i need also would it have problems with the VATS.

 

Going to need a new tune for the 350 anyway ( unless you have a 91 350 memcal which will have VATS on it ) so get a custom chip with the VATS deleted along with other mods like fan on temps change

 

So it would come out kinda pricey doing all of this

 

$150 for a custom chip from PCM forless

 

If you are serious about doing this, come by and I will clue you in as to what's involved. I have done several.

No charge....

 

The car is not in running condition since it hasn't get smogged yet, so is there any other way

 

Dyno Don can you please pm me a quote for the swap i have the tpi system and all the sensors i need

 

Ive just completed a tbi305 to tpi350 conversion just a few months ago, its more time consuming then expensive if you plan on doing most of the work yourself. The wiring harness was biggest issue. A company "Howell Engine Developments, Inc" located in Michigan took my tbi harness in the rough shape that it was and rework it to new and converted it to tpi speed density. I paid somewhere around 300 for all the harness work and another 50 for the computer swap out, they gave me a comp that would work for my application. That alone made the whole conversion easier. Pretty much plug-n-play

 

I did this swap as well.
You will need to replace the fuel pump for a high pressure one, also your exhaust is designed for a 305 and may be inadequate, the 350 uses larger diameter pipe and I think the exhaust manifolds are bigger as well.
Also the throttle cable and transmision kick-down cable will need to be changed, the tbi ones are too short.

 

Was it worth doing the swap to tpi and have any of you guys have problems i am thinking of buying a harness from a 90 and its SD but not sure if it will work. Were can i find Howell Engine Developments, Inc to email him

 

Yes the end product was worth it, but getting there was a major pita, and a money pit, at least in my case anyway.
If I knew then what I know now, I may have just put a 305 tbi back in it and driven it 'till it wouldn't go anymore.

 

I was thinking of staying with the tbi and just putting a cam and porting my heads with the money i would spend to swap in a tpi what do you guys recommend me to do